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-Dominant- [34]
3 years ago
12

150.0 grams of an isotope with a half-life of 36.0 hours is present at time zero. How long will it take

Chemistry
1 answer:
leonid [27]3 years ago
5 0

Given :

Initial mass , a = 150 gm .

Half time ,

t_{\dfrac{1}{2}}=36 \ hours.

Final mass , x = 18.75 gm .

To Find :

The time taken to decay 18.75 gm .

Solution :

We know , time taken is given by :

t=\dfrac{1}{k}\times ln(\dfrac{a}{a-x})

Here , k is a constant given by :

k=\dfrac{0.693}{t_{\dfrac{1}{2}}}\\\\\\k=\dfrac{0.693}{36}

Putting all given value in above equation :

We get :

t=\dfrac{36}{0.693}\times ln(\dfrac{150}{150-18.75})\\\\t=6.94\ hours

Therefore , time taken is 6.94 hours .

Hence , this is the required solution .

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<span>11.11moles x 6.01kJ/mole = 66.78 kJ heat just to melt the ice to water </span>
<span>if you are just looking for the heat to melt the sample of ice, this is where you stop. </span>

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<span>200g x 4.187J/g-ºC x 65ºC = 54431J or 54.431kJ energy to raise the water from 0ºC to 65ºC </span>

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6 0
3 years ago
Read 2 more answers
Write formulas for compounds formed from these pairs of ions.
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Answer:

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Explanation:

8 0
3 years ago
Gaseous methane reacts with gaseous oxygen gas to produce gaseous carbon dioxide and gaseous water . If of carbon dioxide is pro
yaroslaw [1]

The question is incomplete, the complete question is;

Gaseous methane (CH4) reacts with gaseous oxygen gas (O2) to produce gaseous carbon dioxide (CO2) and gaseous water (H2O). If 28.2 g of carbon dioxide is produced from the reaction of 15.1 g of methane and 81.2 g of oxygen gas, Calculate the percent yield of carbon dioxide. Be sure your answer has the correct number of significant digits in it.

Answer:

71.1%

Explanation:

The balanced reaction equation must first be written;

CH4 (g) + 2O2 (g) → CO2 (g) + 2H2O (g)

Let us obtain the number of moles of carbon dioxide corresponding to 28.2 g

Number of moles = mass/ molar mass= 28.2/44.01 g/mol = 0.64 moles of CO2

Next, we obtain the limiting reactant. This is the reactant that yields the least amount of product.

For methane;

Number of moles in 15.1 g= mass/molar mass= 15.1/16gmol-1 = 0.9 moles

From the reaction equation;

1 mole of methane yields 1 mole of carbon dioxide

Hence 0.9 moles of methane yields 0.9 moles of carbon dioxide.

For oxygen

Number of moles of oxygen corresponding to 81.2 g of oxygen= mass/ molar mass= 81.2g/32gmol-1 = 2.5 moles of oxygen

From the reaction equation;

2 moles of oxygen gas yields 1 mole of carbon dioxide

2.5 moles of oxygen gas yields 2.5 × 1 /2 = 1.25 moles of carbon dioxide.

Methane is the limiting reactant.

Theoretical yield of carbon dioxide= 0.9 moles

Actual yield of carbon dioxide= 0.64 moles

% yield = actual yield/ theoretical yield × 100

% yield= 0.64/0.9 ×100

% yield = 71.1%

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3 years ago
Calculate the pH of a 0.0224M HCl solution.
kap26 [50]

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For a 0.0224M HCl solution the concentration of the hydrogen ions,

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pH = −log[H+]

Substituting H+ = 0.0224 into the equation

pH = - log[0.0224]

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pH = 1.65

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What distinguishes science from other disciplines that do not use scientific methods?
rewona [7]

Correct Answer: A. Science relies on observation, measurement, and experimentation.

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